KR20130108105A - Method for allowing terminal to report measurement result for mdt to base station in wireless communication system and device therefor - Google Patents

Abstract

PURPOSE: A method of enabling a terminal to report a measurement result for a minimization of drive test (MDT) to a base station in a wireless communication system and an apparatus therefor are provided to enable the terminal to report the MDT measurement result to the base station. CONSTITUTION: User Equipment (UE) receives MDT set up information from an evolved Node B (eNB) (701). Based on the MDT set up information, the UE performs the cell measurement. Based on a valid point, which precedes a second interval from a storage point, the UE stores the cell measurement result in a MDT log for each storage point of a first interval unit included in the MDT set up information (702). The UE reports the MDT log, which stores the cell measurement result, to the eNB (703).

Description

METHOD FOR ALLOWING TERMINAL TO REPORT MEASUREMENT RESULT FOR MDT TO BASE STATION IN WIRELESS COMMUNICATION SYSTEM AND DEVICE THEREFOR}

The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for reporting a result of a Minimization of Drive Test (MDT) measurement to a base station in a wireless communication system, and an apparatus therefor.

As an example of a wireless communication system to which the present invention can be applied, a 3GPP LTE (Third Generation Partnership Project) Long Term Evolution (LTE) communication system will be schematically described.

1 is a diagram schematically showing an E-UMTS network structure as an example of a wireless communication system. The Evolved Universal Mobile Telecommunications System (E-UMTS) system evolved from the existing Universal Mobile Telecommunications System (UMTS), and is currently undergoing basic standardization work in 3GPP. In general, E-UMTS may be referred to as an LTE (Long Term Evolution) system. For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of "3rd Generation Partnership Project (Technical Specification Group Radio Access Network)" respectively.

1, an E-UMTS includes an Access Gateway (AG) located at the end of a User Equipment (UE), a Node B (eNode B), and an E-UTRAN, . The base station may transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service.

One or more cells exist in one base station. The cell is set to one of the bandwidths of 1.25, 2.5, 5, 10, 15, 20Mhz and the like to provide downlink or uplink transmission service to a plurality of UEs. Different cells may be configured to provide different bandwidths. The base station controls data transmission and reception for a plurality of terminals. The base station transmits downlink scheduling information for downlink (DL) data, and notifies the UE of time / frequency region, coding, data size, and HARQ related information to be transmitted to the UE. In addition, the base station transmits uplink scheduling information to uplink (UL) data, and notifies the UE of time / frequency domain, coding, data size, and HARQ related information that the UE can use. An interface for transmitting user traffic or control traffic may be used between base stations. The Core Network (CN) can be composed of an AG and a network node for user registration of the UE. The AG manages the mobility of the UE in units of a tracking area (TA) composed of a plurality of cells.

Wireless communication technologies have been developed to LTE based on WCDMA, but the demands and expectations of users and operators are continuously increasing. In addition, as other radio access technologies continue to be developed, new technological evolution is required to be competitive in the future. Reduced cost per bit, increased service availability, the use of flexible frequency bands, simple structure and open interface, and adequate power consumption of the terminal are required.

The present invention provides a method for reporting a result of MDT measurement to a base station by a terminal in a wireless communication system and an apparatus therefor.

According to an embodiment of the present invention, in a wireless communication system, a method for reporting a measurement result of a Minimization of Drive Test (MDT) to a base station, the method comprising: receiving MDT configuration information from the base station; Performing cell measurement based on the MDT configuration information; Storing the cell measurement result in an MDT log for each storage time point of a first interval unit included in the MDT configuration information, based on a valid time point preceding a second interval from the storage time point; And reporting the MDT log in which the cell measurement result is stored to the base station. The terminal is characterized in that the radio resource control (RRC) idle state.

Preferably, when there are a plurality of cell measurement results within the validity time point and the storage time point, the cell measurement result measured at the time point closest to the storage time point among the plurality of cell measurement results is stored in the MDT log or The average value of the plurality of cell measurement results may be stored in the MDT log.

Meanwhile, when a cell measurement result does not exist within the valid time point and the storage time point, a preset value may be stored in the MDT log, and the preset value is a lowest value among the values indicated by the cell measurement result. Is preferably. Alternatively, the cell measurement result measured at the time point closest to the valid time point among the cell measurement results before the valid time point may be stored in the MDT log, in which case the stored cell measurement result is the measurement result before the valid time point It is preferable to include an indicator indicating in the MDT log.

More preferably, the MDT configuration information includes information about the second interval.

The first interval and the second interval may be defined as a multiple of a discontinuous reception (DRX) period.

According to the embodiments of the present invention as described above, the terminal may report a more reliable MDT measurement result to the base station.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

1 schematically illustrates an E-UMTS network structure as an example of a wireless communication system.
FIG. 2 conceptually illustrates a network structure of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). FIG.
FIG. 3 is a diagram illustrating a control plane and a user plane structure of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard. FIG.
4 is a diagram for explaining a physical channel used in the 3GPP system and a general signal transmission method using the same.
5 is a diagram illustrating a structure of a radio frame used in an LTE system;
6 is a view for explaining a general transmission and reception method using a call message.
7 illustrates a signal flow diagram for performing a Logged MDT technique.
8 is a flowchart illustrating a method of performing a Logged MDT technique in accordance with an embodiment of the present invention.
9 is a conceptual diagram of a Logged MDT technique in accordance with an embodiment of the present invention.
10 illustrates a block diagram of a communication transceiver according to an embodiment of the present invention.

Hereinafter, the structure, operation and other features of the present invention will be readily understood by the embodiments of the present invention described with reference to the accompanying drawings. The embodiments described below are examples in which technical features of the present invention are applied to a 3GPP system.

Although the present specification describes an embodiment of the present invention using an LTE system and an LTE-A system, embodiments of the present invention may be applied to any communication system corresponding to the above definition. In addition, although the present invention is described with reference to the FDD scheme, the embodiments of the present invention can be easily modified to the H-FDD scheme or the TDD scheme.

2 is a conceptual diagram illustrating a network structure of an evolved universal terrestrial radio access network (E-UTRAN). In particular, the E-UTRAN system evolved from the existing UTRAN system. The E-UTRAN is composed of cells (eNBs), and the cells are connected via the X2 interface. The cell is connected to the terminal through the air interface, and is connected to the EPC (Evolved Packet Core) through the S1 interface.

EPC is composed of MME (Mobility Management Entity), S-GW (Serving-Gateway) and PDN-GW (Packet Data Network-Gateway). The MME has information about the access information of the terminal or the capability of the terminal, and this information is mainly used for mobility management of the terminal. The S-GW is a gateway having an E-UTRAN as an end point, and the PDN-GW is a gateway having a PDN (Packet Data Network) as an end point.

FIG. 3 is a diagram illustrating a control plane and a user plane structure of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard. The control plane refers to a path through which control messages used by a UE and a network are transferred. The user plane means a path through which data generated in the application layer, for example, voice data or Internet packet data, is transmitted.

The physical layer as the first layer provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to a medium access control layer (upper layer) through a transport channel. Data moves between the MAC layer and the physical layer over the transport channel. Data is transferred between the transmitting side and the receiving side physical layer through the physical channel. The physical channel utilizes time and frequency as radio resources. Specifically, the physical channel is modulated in an OFDMA (Orthogonal Frequency Division Multiple Access) scheme in a downlink, and is modulated in an SC-FDMA (Single Carrier Frequency Division Multiple Access) scheme in an uplink.

The Medium Access Control (MAC) layer of the second layer provides a service to a radio link control (RLC) layer, which is an upper layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The function of the RLC layer may be implemented as a functional block in the MAC. The Packet Data Convergence Protocol (PDCP) layer of the second layer performs a header compression function to reduce unnecessary control information in order to efficiently transmit IP packets such as IPv4 and IPv6 in a wireless interface with a narrow bandwidth.

The Radio Resource Control (RRC) layer located at the bottom of the third layer is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of radio bearers (RBs). RB denotes a service provided by the second layer for data transmission between the UE and the network. To this end, the terminal and the RRC layer of the network exchange RRC messages with each other.

One cell constituting the base station eNB is set to one of the bandwidths of 1.25, 2.5, 5, 10, 15, 20Mhz and the like to provide a downlink or uplink transmission service to a plurality of terminals. Different cells may be configured to provide different bandwidths.

A downlink transmission channel for transmitting data from a network to a terminal includes a BCH (Broadcast Channel) for transmitting system information, a PCH (Paging Channel) for transmitting a paging message, a downlink SCH (Shared Channel) for transmitting user traffic or control messages, have. In case of a traffic or control message of a downlink multicast or broadcast service, it may be transmitted through a downlink SCH, or may be transmitted via a separate downlink multicast channel (MCH).

Meanwhile, the uplink transmission channel for transmitting data from the UE to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink SCH (shared channel) for transmitting user traffic or control messages. A logical channel mapped to a transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH) Traffic Channel).

4 is a diagram for explaining physical channels used in a 3GPP system and a general signal transmission method using the same.

When the UE is powered on or enters a new cell, the UE performs an initial cell search operation such as synchronizing with the base station (S401). To this end, the terminal receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from a base station and synchronizes with the base station and acquires information such as a cell ID have. Then, the terminal can receive the physical broadcast channel from the base station and acquire the in-cell broadcast information. Meanwhile, the UE can receive the downlink reference signal (DL RS) in the initial cell search step to check the downlink channel state.

After completing the initial cell search, the UE acquires more specific system information by receiving a physical downlink control channel (PDSCH) according to a physical downlink control channel (PDCCH) and information on the PDCCH. It may be (S402).

On the other hand, if the base station is initially connected or there is no radio resource for signal transmission, the mobile station can perform a random access procedure (RACH) on the base station (steps S403 to S406). To this end, the UE may transmit a specific sequence to the preamble through a physical random access channel (PRACH) (S403 and S405), and may receive a response message for the preamble through the PDCCH and the corresponding PDSCH ( S404 and S406). In case of the contention-based RACH, a contention resolution procedure can be additionally performed.

After performing the procedure as described above, the UE performs a PDCCH / PDSCH reception (S407) and a physical uplink shared channel (PUSCH) / physical uplink control channel (Physical Uplink) as a general uplink / downlink signal transmission procedure. Control Channel (PUCCH) transmission (S408) may be performed. In particular, the UE receives downlink control information (DCI) through the PDCCH. Here, the DCI includes control information such as resource allocation information for the UE, and formats are different according to the purpose of use.

Meanwhile, the control information that the UE transmits to the base station through the uplink or receives from the base station includes a downlink / uplink ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI) ) And the like. In the case of the 3GPP LTE system, the UE can transmit control information such as CQI / PMI / RI as described above through PUSCH and / or PUCCH.

5 is a diagram illustrating a structure of a radio frame used in an LTE system.

Referring to FIG. 5, a radio frame has a length of 10 ms (327200 × T _s ) and consists of ten equally sized subframes. Each subframe has a length of 1 ms and is composed of two slots. Each slot has a length of 0.5 ms (15360 x T _s ). Here, T _s represents a sampling time and is represented by T _s = 1 / (15 kHz x 2048) = 3.2552 x 10 ^-8 (about 33 ns). A slot includes a plurality of OFDM symbols in a time domain and a plurality of resource blocks (RB) in a frequency domain. In the LTE system, one resource block includes 12 subcarriers x 7 (6) OFDM symbols. A TTI (Transmission Time Interval), which is a unit time at which data is transmitted, may be defined in units of one or more subframes. The structure of the radio frame is merely an example, and the number of subframes included in a radio frame, the number of slots included in a subframe, and the number of OFDM symbols included in a slot can be variously changed.

Hereinafter, the RRC state and the RRC connection method of the terminal will be described. The RRC state refers to whether or not the RRC of the UE is in a logical connection with the RRC of the E-UTRAN. If connected, the RRC connected state (RRC_CONNECTED), if not connected, the RRC idle state (RRC_IDLE). It is called.

Since the E-UTRAN can grasp the presence of the UE in the RRC connection state on a cell basis, the E-UTRAN can effectively control the UE. On the other hand, the E-UTRAN cannot identify the UE of the RRC idle state in cell units, and the CN manages the TA unit, which is a larger area unit than the cell. That is, in order for the UE in the RRC idle state to receive services such as voice or data from the cell, the UE must transition to the RRC connected state.

In particular, when the user first turns on the power of the terminal, the terminal first searches for an appropriate cell and then stays in an RRC idle state in the cell. The UE which has stayed in the RRC idle state performs the RRC connection establishment process with the RRC of the E-UTRAN only when it is necessary to establish the RRC connection, and transits to the RRC connection state. In this case, when the RRC connection needs to be established, an uplink data transmission is necessary due to a user's call attempt, or when a paging message is received from the E-UTRAN, a response message should be transmitted.

6 is a diagram illustrating a general transmission and reception method using a call message.

Referring to FIG. 6, the call message includes a paging record composed of a paging cause, a terminal identifier, and the like. When receiving the call message, the terminal may perform a discontinuous reception (DRX) for the purpose of reducing power consumption.

Specifically, the network configures a plurality of paging occasions (POs) for each time period called a paging DRX cycle, and a specific terminal can receive only a specific paging opportunity time to obtain a paging message. . The terminal does not receive the paging channel at times other than the specific paging opportunity time and may be in a sleep state to reduce power consumption. One call opportunity time corresponds to one TTI.

The BS and the UE use a paging indicator (PI) as a specific value for informing the transmission of the paging message. The base station may define a specific identifier (for example, Paging-Radio Network Temporary Identity (P-RNTI)) for the purpose of the PI to inform the terminal of the call information transmission. For example, the terminal wakes up every DRX cycle and receives one subframe to know whether a call message appears. If the P-RNTI is present in the L1 / L2 control channel (PDCCH) of the received subframe, the UE may know that there is a call message in the PDSCH of the corresponding subframe. In addition, if the call message has its own terminal identifier (eg, IMSI), the terminal receives the service by responding to the base station (eg, receiving RRC connection or system information).

Now we discuss measurement and measurement reporting.

In the following description, 'measurement' receives a reference signal received from cells located in inter-frequency, intra-frequency, and inter-RAT according to the measurement setting received by the UE from the network, It can be defined as measuring the quality value. In addition, in the following description, the term 'quality' refers to a signal quality or a cell quality grasped through a reference signal received from a measurement target cell.

In connection with the mobility support of the UE in the mobile communication system, the UE continuously and at least discontinuously receives the quality of the serving cell and the neighboring cell that provide the current service. ) Measured every cycle. The terminal reports the cell quality measurement result to the network at an appropriate time, and the network provides the optimum mobility to the terminal through handover.

The terminal may perform measurement for a specific purpose set by the network and report the cell quality measurement result to the network in order to provide information that may help the operator to operate the network in addition to the purpose of mobility support. For example, the terminal receives broadcast information of a specific cell set by the network. The terminal may store a cell identifier of the particular cell (also referred to as a global cell identifier), location identification information (e.g., Tracking Area Code) to which the particular cell belongs and / For example, whether it is a member of a closed subscriber group (CSG) cell).

When the mobile station determines that the quality of a particular region is very poor through measurement, the terminal may report the location information and the cell quality measurement result for the poor quality cells to the network. The network can optimize the network based on the report of the cell quality measurement results of the terminals helping the network operation.

In a mobile communication system with a frequency reuse factor of 1, mobility is mostly between different cells in the same frequency band. Therefore, in order to ensure mobility of the UE, the UE must be able to measure the quality and cell information of neighbor cells having the same center frequency as the center frequency of the serving cell. As such, the measurement of the cell having the same center frequency as that of the serving cell is called intra-frequency measurement. The terminal performs the intra-cell measurement and reports the cell quality measurement result to the network at an appropriate time, so that the purpose of the corresponding cell quality measurement result is achieved.

The mobile communication service provider may operate the network using a plurality of frequency bands. In a case where a service of a communication system is provided through a plurality of frequency bands, in order to guarantee optimal mobility to the UE, the UE can measure the quality and cell information of neighboring cells having center frequencies different from the center frequency of the serving cell . As such, a measurement for a cell having a center frequency different from that of the serving cell is called inter-frequency measurement. The UE should be able to report cell quality measurement results to the network at an appropriate time by performing inter-cell measurements.

If the UE supports measurements on a heterogeneous network, measurements may be made on the cells of the heterogeneous network by setting the BS. Such measurements on heterogeneous networks are referred to as inter-RAT (Radio Access Technology) measurements. For example, the RAT may include UTRAN (UMTS Terrestrial Radio Access Network) and GERAN (GSM EDGE Radio Access Network) conforming to the 3GPP standard, and may also include a CDMA 2000 system conforming to the 3GPP2 standard.

Hereinafter, the Minimization of Drive Test (MDT) technique will be described.

In order to optimize cell coverage, MDT allows operators to measure the quality of a cell using a car. Instead of the conventional method of performing the drive test, the MDT may allow the terminals present in the cell to make measurements and report the results. Through this, it is possible to generate a cell coverage map and minimize the time and cost for network optimization.

There are two types of MDTs: Logged MDT and Immediate MDT. Logged MDT is a method in which a UE performs a measurement for MDT, stores the data in an MDT log, and delivers the data to a network at a specific point in time. Immediate MDT is a method of measuring data for MDT and transmitting the data directly to the network. The difference between the two methods is whether the UE reports the result of the measurement to the base station or stores it and reports it later. In particular, in the case of the UE in the RRC idle state, there is no RRC connection. Can't report, so we use Logged MDT.

7 shows a signal flow diagram for performing the Logged MDT technique.

Referring to FIG. 7, in order to perform a Logged MDT, a UE may first receive a message including a Logged MDT setting from a cell in step 701.

Logged MDT configuration received by the terminal may include a triggering (triggering) setting, the MDT configuration validity duration (duration), the area (area) for performing the MDT, etc. that triggers the logging of the event.

Next, in step 702, upon receipt of the Logged MDT setting, the UE starts a timer for a period in which the Logged MDT setting is valid. Only while the duration timer is in operation, the UE stores the measurement result for the Logged MDT in a predetermined period in the MDT log in the RRC idle state. Here, the preset period is a period for storing the measurement result according to the Logged MDT setting in the MDT log, hereinafter referred to as a logging period, and can be generally expressed as a multiple of the DRX cycle.

On the other hand, when the validity period timer expires, the terminal deletes the MDT configuration. However, the UE further has an opportunity to report the stored MDT cell quality measurement result to the cell by maintaining the stored MDT cell quality measurement result for a predetermined time (for example, 48 hours).

The value measured for the MDT is generally the quality of the cell on which the UE stays (camp on), which is measured by RSRP (Reference Signal Received Power) and RSRQ (Reference Signal Received Quality). When Logged MDT is configured in the terminal, the quality of the cell is measured and stored in the RRC idle state, and then the MDT measurement value is reported to the network.

The operator synthesizes the MDT measurement values received from the various terminals and prepares a coverage map that shows the distribution of service availability and quality of service over the entire area in which the operator provides the service. It can be utilized. For example, if a coverage problem of a specific area is reported from the terminal, the operator may expand the coverage of the corresponding area cell by increasing the transmission power of the base station providing the service of the corresponding area.

The cell quality measurement result for MDT may be used interchangeably as a log, a terminal log value, a measurement value, a cell quality measurement result, and the like, but for simplicity of the specification, hereinafter, it is referred to as an MDT measurement result.

Finally, the process of reporting the MDT measurement result of step 703 will be described.

When the terminal performs the logged MDT and there is a MDT measurement result stored in the terminal, when the terminal establishes an RRC connection (that is, during the RRC connection establishment procedure), the MDT measurement result is stored in the network. RRC connection setup complete).

The network that receives the MDT measurement result from the terminal sends a command to the terminal to transmit the stored MDT cell quality measurement result, and correspondingly, the terminal transmits the stored MDT measurement result to the network.

In addition to making an RRC connection, the UE may inform the network through an RRC connection re-establishment complete message that the MDT measurement result is stored even when the UE performs RRC connection re-establishment. In addition, when the UE handovers from a serving cell to a target cell, the UE may inform that the MDT measurement result is stored in the target cell through a handover completion message.

On the other hand, in the case of the Logged MDT technique, a cycle for storing the measurement result according to the above-described Logged MDT configuration in the MDT log, that is, a logging cycle and a terminal for performing an actual measurement may be different. In particular, the quality measurement for the neighbor cell of the terminal may be performed at a constant measurement period according to the internal operation of the terminal, or may be performed when a specific condition is satisfied.

Therefore, when the UE stores the measurement result in the MDT log according to the set logging period, there may occur a case in which the measurement for the neighbor cell is not performed. In this case, the UE is the most recent result measured after the previous MDT log storage. The value is determined to be valid and the measurement result is stored in the log.

In addition, the location information received from the Global Navigation Satellite System (GNSS) can also be stored in the log along with the quality measurement results. This information is also determined to be the most recent value of the location information since the previous log storage, and the measurement results are logged. Will be stored in.

If the logging period is set to a very long value, the difference between the point in time at which the measurement result (or location information) is obtained and the point in time at which the result is stored in the log may be large, even if the measurement value is obtained most recently. That is, the error of the MDT log result has a problem that becomes larger as the logging period is longer. The larger the error is, the more difficult the network obtains a good coverage map, and the network optimization is performed based on inaccurate results, which may reduce the performance of the network.

Therefore, the present invention is to propose a method for maintaining a certain reliability of the information in the terminal performing the Logged MDT technique to store the measurement results in the MDT log. In particular, in storing the measurement result in the MDT log, it is characterized in that it is limited to the measurement results obtained in a predefined window (window).

8 is a flow chart illustrating a method of performing a Logged MDT technique in accordance with an embodiment of the present invention.

Referring to FIG. 8, first, the UE in the RRC idle state determines whether it is time to store the measurement result in the MDT log. The time point to be stored in the MDT log may be defined as a specific period, that is, a logging period.

Subsequently, the terminal checks whether a measurement result for MDT exists in a predetermined window in step 801. The window may be a certain amount of time and may be delivered by being included in a Logged MDT configuration from a network, or may be a predefined value, and may be expressed as a multiple of a DRX cycle as well as a logging cycle. The start time of the window is preferably defined as a time to be stored in the MDT log, that is, a subframe preceding the size of the window in the subframe. In other words, the end point of the window is when the measurement results are stored in the MDT log.

If there is a measurement result in the window, a measurement result for storing in the MDT log is selected in step 802. In particular, if there are a plurality of measurement results in the window, the terminal may calculate and select an average value of the plurality of measurement results, or select the most recent measurement result among the plurality of measurement results.

In addition, if there is no measurement result in the window, in step 803 the terminal selects a specific value indicating that there is no measurement result in the window. In this case, the specific value may be set to a lowest value of the measurement results, through which the base station may indirectly recognize that there is no good measurement result in the window. Alternatively, the terminal may select the most recent measurement result outside the window, and in this case, the indicator may be included together that the selected measurement result is the measurement result outside the window. In constructing the cell coverage map, the base station may consider whether the measurement result is used through an indicator that the measurement result is outside the window.

Finally, the terminal stores the measurement result selected in step 802 or step 803 in the MDT log in step 804.

As described above, when the terminal stores the measurement result in the MDT log according to the MDT setting, time and location information may be stored together. In particular, the above-described embodiment may also be applied when the location information is stored in the MDT log.

That is, if the location information exists in the window, the location information for storing in the MDT log is selected. In particular, if there is a plurality of location information in the window, the terminal may select the most recent location information among the plurality of location information, or may select the most accurate location information.

Similarly, if the location information does not exist in the window, the terminal selects a specific value indicating that there is no location information in the window or does not select any location information. Alternatively, the terminal may select the latest location information outside the window, and in this case, the indicator may be included together that the selected location information is location information outside the window.

On the other hand, in order to match the measurement time between the measurement result and the position information, if there are a plurality of measurement results in the window, the measurement result obtained at the time closest to the time of receiving the position information among the plurality of measurement results is selected.

9 is a conceptual diagram of a Logged MDT technique according to an embodiment of the present invention.

Referring to FIG. 9, the terminal repeatedly stores the measurement result in the MDT log at a logging period during the MDT configuration valid period. In this case, according to an embodiment of the present invention, the terminal may store the measurement results limited to the measurement results obtained in a predefined window.

Specifically, in the logging periods 901 and 902, two measurement results exist in the window, and the terminal stores the average value or the most recent measurement result of the plurality of measurement results in the MDT log.

Also, in the logging periods 903 and 905, since there is no measurement result in the window, the terminal stores a specific value in the MDT log indicating that there is no measurement result in the window. Alternatively, the terminal may select the most recent measurement result outside the window and store it in the MDT log. In this case, the indicator may be stored together in the MDT log that the selected measurement result is the measurement result outside the window.

According to the present invention, the reliability of the measurement result stored in the MDT log is independent of the logging period, and in particular, has an error equal to the size of the window at the time point stored in the MDT log. Therefore, the reliability of the result stored in the MDT log can be maintained at all times regardless of the logging cycle.

10 illustrates a block diagram of a communication transceiver according to an embodiment of the present invention. The transceiver may be part of a base station or a terminal.

Referring to FIG. 10, the transceiver 1000 includes a processor 1010, a memory 1020, an RF module 1030, a display module 1040, and a user interface module 1050.

The transceiver 1000 is shown for convenience of description and some modules may be omitted. In addition, the transceiver 1000 may further include necessary modules. In addition, some modules in the transceiver 1000 may be classified into more granular modules. The processor 1020 is configured to perform an operation according to the embodiment of the present invention illustrated with reference to the drawings.

In detail, when the transceiver 1000 is part of a base station, the processor 1020 may generate a control signal and perform mapping to a control channel set in a plurality of frequency blocks. In addition, when the transceiver 1000 is part of a terminal, the processor 1020 may check a control channel directed to the user from signals received from the plurality of frequency blocks and extract a control signal therefrom.

Thereafter, the processor 1020 may perform a required operation based on the control signal. Detailed operations of the processor 1020 may refer to the contents described with reference to FIGS. 1 to 9.

The memory 1020 is connected to the processor 1010 and stores an operating system, an application, program code, data, and the like. The RF module 1030 is connected to the processor 1010 and performs a function of converting a baseband signal into a radio signal or converting a radio signal into a baseband signal. To this end, the RF module 1030 performs analog conversion, amplification, filtering and frequency up-conversion, or a reverse process thereof. The display module 1040 is connected to the processor 1010 and displays various information. The display module 1040 may use well-known elements such as, but not limited to, a liquid crystal display (LCD), a light emitting diode (LED), and an organic light emitting diode (OLED). The user interface module 1050 is connected to the processor 1010 and may be configured with a combination of well-known user interfaces such as a keypad, a touch screen, and the like.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

In this document, the embodiments of the present invention have been mainly described with reference to the data transmission / reception relationship between the terminal and the base station. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Industrial availability

In the above-described wireless communication system, a method for reporting a MDT measurement result to a base station and an apparatus therefor have been described with reference to an example applied to a 3GPP LTE system. However, the method may be applied to various wireless communication systems in addition to the 3GPP LTE system. Do.

Claims (10)

In the method of the terminal reports the result of the measurement of the MDT (Minimization of Drive Test) to the base station,
Receiving MDT configuration information from the base station;
Performing cell measurement based on the MDT configuration information;
Storing the cell measurement result in an MDT log for each storage time point of a first interval unit included in the MDT configuration information, based on a valid time point preceding a second interval from the storage time point; And
And reporting the MDT log in which the cell measurement result is stored to the base station.
How to report MDT measurement results. The method of claim 1,
Storing the cell measurement result in the MDT log,
If there are a plurality of cell measurement results within the validity time point and the storage time point, storing the cell measurement result measured at a time point closest to the storage time point among the plurality of cell measurement results in the MDT log; Characterized in that
How to report MDT measurement results. The method of claim 1,
Storing the cell measurement result in the MDT log,
Storing a mean value of the plurality of cell measurement results in the MDT log when a plurality of cell measurement results exist within the validity time point and the storage time point.
How to report MDT measurement results. The method of claim 1,
Storing the cell measurement result in the MDT log,
Storing a predetermined value in the MDT log when a cell measurement result does not exist within the valid time point and the storage time point.
How to report MDT measurement results. 5. The method of claim 4,
The preset value is,
Characterized in that the cell measurement result is the lowest value (Lowest Value) indicated,
How to report MDT measurement results. The method of claim 1,
Storing the cell measurement result in the MDT log,
If the cell measurement result does not exist within the validity time point and the storage time point, storing the cell measurement result measured at the time point closest to the valid time point among cell measurement results before the validity time point in the MDT log; Characterized by
How to report MDT measurement results. The method according to claim 6,
The MDT log is,
And an indicator indicating that the stored cell measurement result is a measurement result before the validity time point.
How to report MDT measurement results. The method of claim 1,
The MDT setting information,
Characterized in that the information on the second interval,
How to report MDT measurement results. The method of claim 1,
The terminal,
RRC (Radio Resource Control) Idle state, characterized in that,
How to report MDT measurement results. The method of claim 1,
The first interval and the second interval,
Characterized in that the unit is defined in multiples of the discontinuous reception (DRX) cycle,
How to report MDT measurement results.

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